String.cpp

#include "String.h"

std::allocator<char> String::alloc;

String::String(const_iterator ci) : String() {
  while (ci && *ci != '\0')
    push_back(*ci++);
}

String::String(std::initializer_list<char> il) : String() {
  for (const auto &c : il)
    push_back(c);
}

void String::push_back(const_reference c) {
  if (size() == capacity())
    reallocate(empty() ? 1 : 2 * capacity());
  alloc.construct(first_free++, c);
}

void String::pop_back() {
  if (!empty())
    alloc.destroy(--first_free);
}

void String::reserve(size_type n) {
  if (n > capacity()) {
    reallocate(n);
  }
}

void String::resize(size_type n, const_reference c) {
  if (n > size()) {
    for (int i = n - size(); i > 0; --i)
      push_back(c);
  } else if (n < size()) {
    for (int i = size() - n; i > 0; --i)
      pop_back();
  }
}

void String::reallocate(size_type n) {
  auto new_first_elem = alloc.allocate(n);
  auto new_first_free = new_first_elem;
  for (auto it = begin(); it != end(); ++it)
    alloc.construct(new_first_free++, std::move(*it));
  // the above three lines of code can be replaced by the following code:
  //auto new_first_free = std::uninitialized_copy(
  //    std::make_move_iterator(begin()),
  //    std::make_move_iterator(end()), new_first_elem);
  free();
  first_elem = new_first_elem;
  first_free = new_first_free;
  cap = first_elem + n;
}

void String::free() {
  while (!empty())
    alloc.destroy(--first_free);
  alloc.deallocate(first_elem, capacity());
  first_elem = first_free = cap = nullptr;
}

String::String(const String &rhs) {
  first_elem = alloc.allocate(rhs.size());
  first_free = cap = std::uninitialized_copy(rhs.begin(), rhs.end(),
                                             first_elem);
}

String::~String() {
  free();
}

String &String::operator=(const String &rhs) {
  auto new_first_elem = alloc.allocate(rhs.size());
  auto new_first_free = std::uninitialized_copy(rhs.begin(), rhs.end(),
                                                new_first_elem);
  free();
  first_elem = new_first_elem;
  first_free = cap = new_first_free;
  return *this;
}

String &String::operator=(const_iterator ci) {
  *this = String(ci);
  return *this;
}

std::string String::str() const {
  return std::string(cbegin(), cend());
}